Golang的內存數據庫：go-memdb

實現了一個基于不變基數樹(radix tree)的內存數據庫。該數據庫提供了來自ACID的原子性，一致性和隔離性。因為它是在內存中，所以不提供持久存儲。

該數據庫提供了以下特性:

• Multi-Version Concurrency Control (MVCC) - By leveraging immutable radix trees the database is able to support any number of concurrent readers without locking, and allows a writer to make progress.

• Transaction Support - The database allows for rich transactions, in which multiple objects are inserted, updated or deleted. The transactions can span multiple tables, and are applied atomically. The database provides atomicity and isolation in ACID terminology, such that until commit the updates are not visible.

• Rich Indexing - Tables can support any number of indexes, which can be simple like a single field index, or more advanced compound field indexes. Certain types like UUID can be efficiently compressed from strings into byte indexes for reduces storage requirements.

// Create a sample struct
type Person struct {
    Email string
    Name  string
    Age   int
}

// Create the DB schema
schema := &memdb.DBSchema{
    Tables: map[string]*memdb.TableSchema{
        "person": &memdb.TableSchema{
            Name: "person",
            Indexes: map[string]*memdb.IndexSchema{
                "id": &memdb.IndexSchema{
                    Name:    "id",
                    Unique:  true,
                    Indexer: &memdb.StringFieldIndex{Field: "Email"},
                },
            },
        },
    },
}

// Create a new data base
db, err := memdb.NewMemDB(schema)
if err != nil {
    panic(err)
}

// Create a write transaction
txn := db.Txn(true)

// Insert a new person
p := &Person{"joe@aol.com", "Joe", 30}
if err := txn.Insert("person", p); err != nil {
    panic(err)
}

// Commit the transaction
txn.Commit()

// Create read-only transaction
txn = db.Txn(false)
defer txn.Abort()

// Lookup by email
raw, err := txn.First("person", "id", "joe@aol.com")
if err != nil {
    panic(err)
}

// Say hi!
fmt.Printf("Hello %s!", raw.(*Person).Name)

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